Open .tiff, set projection, then re-save in Python with GDAL

Question

I am trying to set the projections of a .tiff file from another file with GDAL in Python. I successfully set the projections, but how do I re-save the .tiff afterwards?

Here is my code:

ds = gdal.Open('satellite_image.tif')
prj = ds.GetProjection()

roads = gdal.Open('road_lines.tiff')
roads.SetProjection(prj)

Answer 1

You need to open the second file in update mode, then dereference it to save and close it.

roads = gdal.Open('road_lines.tiff', gdal.GA_Update)
roads.SetProjection(prj)
del roads  # save, close

Another method to apply a projection to a GeoTIFF file is to use the geotifcp utility.